There's no method by which a completely mod-free repaired game in a completely new user folder can access your old Sims. It sounds like you might have other issues interfering.
Please try this:
- Make sure OneDrive, iCloud, or any other syncing software is completely disconnected from Sims. You'll find support for these issues in the Sims 4 Technical Support forums for Mac and PC.
- Rename this folder: Documents > Electronic Arts > The Sims 4
- Run a Game Repair
- Now start the game. It should behave as if you have never played before. Make a save -- "New" will be the only option.